So MIDI learn didn't catch it?
If not try the action mapping window and see if it lists NRPN events correctly. If it doesn't, it's unlikely that OTQ currently supports it. I suspect the devs would be willing to add that feature, but I have absolutely no idea how difficult that would be or how long a wait time that would involve.
There might also be a hardware or software solution that could translate an NRPN message into a standard RPN/CC event or value, but I haven't had much experience "translating" MIDI events. Some DAWs support automated MIDI editing, for example, which might enable the functionality you're looking for if OTQ doesn't have it built in right now.
Without an MDS65, I can't really do more testing of that, unfortunately. (I don't think any of my MIDI devices have NRPN signals that are transmitted through the line as opposed to just being internal.)
Spotify:
https://open.spotify.com/artist/2xHiPcCsm29R12HX4eXd4JPianoteq Studio & Organteq
Casio GP300 & Custom organ console